Heat assisted magnetic recording (HAMR) generally refers to the concept of locally heating a recording medium to reduce the coercivity of the recording medium so that the applied magnetic writing field can more easily direct the magnetization of the recording medium during the temporary magnetic softening of the recording medium caused by the heat source. Heat assisted magnetic recording allows for the use of small grain media, which is desirable for recording at increased areal densities, with a larger magnetic anisotropy at room temperature to assure sufficient thermal stability. By heating the medium, the material's magnetic crystalline anisotropy energy density or the coercivity is reduced such that the magnetic write field is sufficient to write to the medium. Once the medium cools to ambient temperature, the medium has a sufficiently high value of coercivity to assure thermal stability of the recorded information.
It is well-known in magneto-optical (MO) recording that there are media that require heating in order for the information to be retrieved from a disc. For example, MO recording media comprised of TbFeCO is extremely thermally stable due to the divergence of the coercivity of the media at room temperature. However, at room temperature the magnetization is zero making it impossible for read back using a magnetoresistive sensor. In order to read this type of medium with a magnetoresistive (MR) sensor, the medium first needs to be heated to induce a magnetization in the film. Other media that can use thermally assisted read back include magnetic super resolution media, MAMMOS (Magnetic Amplifying MO System) media, and various exchange spring type media.
Transducers have been proposed for use in heat assisted magnetic recording (HAMR) wherein the light delivery system is aligned only with the writer and not the reader. Furthermore, given the complexity of the alignment problem, it does not seem likely that it will be possible to design a transducer where the reader and writer can be simultaneously aligned with the light delivery element.
There is a need for a transducer assembly that can be used in storage devices using thermally assisted writing and read back.